I've recently located a relatively inexpensive source for Purple Hearts and other decorations. Purple Hearts are in the original (World War II Style) leatherette presentation cases with "Purple Heart" embossed in gold-leaf on the top of the case. Other decorations and service medals are mailed in protective plastic sleeves.
You can obtain decorations and medals free of charge from the records center in St. Louis BUT there's a backlog of almost 200,000 requests and the average wait is now almost three years. Also, Purple Hearts (and all other decorations) are issued in the newer-type, generic plastic presentation cases.
Also available: a limited number of Air Medals in the original WWII-Type presentation cases.